The study looked at more than 400 mice in apartment building basements in Manhattan, Queens, Brooklyn and the Bronx. Researchers took swabs of the mice, gathered faeces from the traps, and conducted a battery of genetic tests.

As you might expect, the mice carried many bacteria, including C. difficile, E. coli, Shigella, as well as Salmonella. Sequencing of faeces revealed 36 viruses from 18 families and 21 genera, including at least six never seen before viruses (novel virus).

More importantly, they found evidence of genes that encourage resistance to common antibiotics.